Microcurrent Intensity Explained, Microamps, Milliamps and the Motor Threshold
Medically reviewed by
4 independent reviewers
Andrew Conrad Barile, PT, DPT
Doctor of Physical Therapy (DPT) | Licensed Physical Therapist (PT) | CEO and Founder, Xtreem Pulse LLC
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Dr. Andrew Conrad Barile is a Doctor of Physical Therapy and the CEO and Founder of Xtreem Pulse LLC, the engineering company behind PureLift. He earned his Doctorate in Physical Therapy from Daemen College and is a licensed physical therapist.
He brings over two decades of clinical and entrepreneurial experience across physical therapy, craniosacral therapy and medical device innovation, built on a working knowledge of human anatomy and muscle physiology.
For PureLift LAB he reviews how current is delivered across all ten levels, from sub-sensory nanocurrent and skin-level microcurrent to motor-level EMS, and how the Infuse pass fits into the same ten-minute routine.
Bertica M. Rubio, M.D.
Board-Certified Physician, Dartmouth Medical School | Medical Director, Antiaging Regenerative Medicine Clinic
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Dr. Bertica M. Rubio is a board-certified physician and Medical Director of the Antiaging Regenerative Medicine Clinic in Redlands, California. She earned her Doctor of Medicine from Dartmouth Medical School and completed her pediatrics residency at UC Irvine Medical Center.
With decades of clinical experience, she specialises in age management medicine, regenerative medicine, wound healing and growth factor therapies, and her practice integrates evidence-based medical science with advanced aesthetic treatment.
For PureLift LAB she reviews articles for medical accuracy across the whole dial, from the gentle nanocurrent and microcurrent settings through to muscle-level EMS and the Infuse pass.
Daniel Grinberg, MD, FACS
Board-Certified Otolaryngologist | Head and Neck Surgeon | Fellow, American College of Surgeons | Mount Sinai
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Daniel Grinberg, MD, FACS is a board-certified otolaryngologist and head and neck surgeon at ENT and Allergy Associates in West Nyack, New York. He earned his medical degree from Columbia University College of Physicians and Surgeons.
He completed his otolaryngology residency at New York University Medical Center, serves as Assistant Clinical Professor at Mount Sinai School of Medicine, and is a Fellow of both the American College of Surgeons and the American Academy of Otolaryngology.
For PureLift LAB he brings a wider clinical lens, connecting at-home facial stimulation from microcurrent to EMS to the anatomy underneath, with the same rigour we apply to every device specification.
Prof. Dr. med. Ivo Buschmann
Chair of Angiology, Medizinische Hochschule Brandenburg | Clinic Director, University Clinic for Angiology
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Prof. Dr. med. Ivo Buschmann is Chair of Angiology at the Medizinische Hochschule Brandenburg Theodor Fontane and Clinic Director of the University Clinic for Angiology at the Brandenburg University Hospital.
He trained at the University of Hamburg, was a Max Planck Society Fellow at the Max Planck Institute for Heart and Lung Research, and held senior consultant posts at the Charite Universitatsmedizin Berlin before his appointment as Chair in 2016.
One of Europe's leading authorities on arteriogenesis, with over 150 peer-reviewed publications and US and EU patents, he reviews for PureLift LAB how the evidence on electrical stimulation is read and where its limits lie.
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Every facial device prints an intensity figure, and the units are doing more work than most shoppers realise.
This article makes the numbers readable, such as:
- What a microamp and a milliamp actually are
- The published figure for each major device
- The motor threshold, and why it is the only line that matters
- Why some brands publish no figure at all
- Why more output stops helping above a certain point
and many more!
Every figure here comes from a brand's own site or its FDA clearance document.
Key Points:
A microamp is a millionth of an amp; a milliamp is a thousandth, so one milliamp is a thousand microamps.
680 µA and 7 mA look similar on a page and are about a tenfold difference.
The motor threshold is the only boundary that changes what a device can do, and it is where a tingle becomes a contraction.
Several major brands publish no output figure on their own product pages, so the number has to come from their FDA documents.
Above the threshold, more output adds discomfort rather than results.
The units, plainly
A microamp, written µA, is one millionth of an amp.
A milliamp, written mA, is one thousandth of an amp, so a single milliamp is a thousand microamps.
Those two abbreviations differ by one letter and by a factor of a thousand, which is why a spec sheet can look like a close contest when it is not.
680 µA against 7 mA reads as 680 against 7 if you skim it, and the real relationship is 680 against 7,000.
What the major devices publish
FOREO BEAR 2 at $399 publishes 680 µA, which is high for the microcurrent category and worth crediting.
Therabody TheraFace PRO at $419.99 comes in at 500 µA, and ZIIP Halo at $399.99 at 309 µA.
NuFACE Trinity+ at $395 sits between 170 and 200 µA.
Worth knowing where those last three came from: NuFACE, ZIIP and Therabody do not print an output figure on their own product pages, so the numbers above are taken from their FDA clearance documents.
PureLift publishes its figures directly, 7 mA at 500 ohms on Face and Pro, 7.7 mA on Pro Edition, and 9 mA on Pro Plus and GLOW, which is 7,000 to 9,000 µA in the other unit.
Why a missing figure tells you something
A brand that describes its device as powerful, professional-grade or clinical-strength without printing a number is asking you to accept an adjective instead of a measurement.
The figure is not commercially sensitive, since it appears in the FDA document anyone can look up, so declining to publish it is a choice about presentation rather than a necessity.
An unpublished figure does not mean a device is weak, and it does mean you cannot compare it without doing the digging yourself.
The motor threshold, the only line that matters
A review of kilohertz-frequency stimulation describes three thresholds present in everyone, the point you first feel the current, the point the muscle moves, and the point it becomes painful (Ward 2009).
The second of those is the motor threshold, and it is the boundary that separates a device working on your skin from a device working on your muscle.
Every device in the microamp range above sits below it across its entire dial, which is why they produce a tingle rather than a visible twitch, and that is not a failure since skin-level work is what they are built for.
On a PureLift the threshold is crossed at level 3, with nanocurrent at level 1 and microcurrent at level 2 sitting below it, so one dial covers both sides of the line.
Why more stops helping
Once the contraction is visible in the mirror, the muscle is doing the work, and pushing the dial higher moves you toward the third threshold rather than toward a better result.
Higher intensity also brings fatigue on sooner, so the last minutes of a punishing session are doing less than the first ones did.
The trial evidence in this category came from modest protocols repeated consistently, not from anyone maximising a dial (Kavanagh 2012).
That is why the milliamps at the top of the PureLift range are headroom above the level most people settle at, and why the real reasons to move up the range are the shape in your hand, the diamond-faceted probe and PDM++ on the 9 mA models, and the light on GLOW.
What the number does not tell you
A published maximum is measured into a fixed resistance in a laboratory, commonly 500 ohms, and your face is not a resistor.
What actually reaches the muscle depends on contact, how well the conductive serum covers the skin, where you place the probe and your own tissue, which is why honest copy says up to.
A dry or patchy serum layer wastes more current than any specification difference between two devices, so the cheapest improvement available to you is more serum rather than a higher setting.